This invention concerns wound dressings particularly as wound treatment means in the granulation and epithelization phase. These wound dressings are useful for moist treatment of wounds in particular. The present invention further concerns a process for producing these wound dressings.
The healing of skin wounds is based on the ability of the skin to regenerate epithelium and also connective and supporting tissue. Regeneration itself is characterized by a complex interplay of overlapping cellular activities which advance the healing process step by step. Three essential healing phases of a wound have been described in the literature irrespective of the type of wound. They include the inflammatory or exudative phase for blood coagulation and wound cleaning (phase 1, cleaning phase), the proliferative phase for building granulation tissue (phase 2, granulation phase) and the differentiation phase for epithelization and scar formation (phase 3, epithelization phase).
Numerous proposals for augmenting individual wound healing phases are described in the literature. Especially wound dressings comprising polyurethane foams have for some time been the subject matter of numerous articles in the technical literature and also of patent documents. The European patents EP 457 977 B1, EP 486 522 B1, EP 541 390 B1, EP 541 391 B1, EP 570 430 B1, EP 665 856 B1, EP 691 113 B1, EP 693 913 B1 or EP 1 082 146 B1, for instance, describe wound dressings having various constructions where the absorbent layer comprises a polyurethane foam. These polyurethane foams can become adherent to the healing wound when new cells/tissues grow into the pores of the foams.
In addition, the European patents EP 855 921 B1 and EP 1 156 838 B1 disclose wound dressings comprising a polyurethane foam coated with a hydrophobic silicone gel. This silicone gel is said to inhibit the adherence of the wound to the polyurethane foam.
Furthermore, the international applications WO 02/38 097 A1, WO 02/47 761 A1, WO 03/011 352 A1, WO 03/086 255 A1, WO 2004/052 415 A1 or EP 1 658 865 A1 describe wound dressings comprising a hydrogel and a polyurethane foam. The polyurethane foams used are dry.
Proceeding from these described and commercially available wound dressings, the present invention has for its object to provide an improved wound dressing particularly for wound healing in the granulation and/or epithelization phase. It is a further object of the present invention to provide a wound dressing that influences the pathological state of a wound such that a normal, natural wound healing process can occur. To this end, the wound dressing shall provide a sufficient amount of moisture to the wound and at the same time have a good absorptive capacity. It is yet a further object of the present invention to provide a wound dressing that exerts little if any shearing forces on a wound to be treated.